Many people have difficulty understanding the difference between the Xen Hypervisor, XenServer, and XAPI. In this session, James Bulpin, Director of Technology for XenServer, and Russell Pavlicek, Evangelist for the Xen Project, will attempt to clarify what each project is, what it does, and how it compares with the others. We will cover some of the basic features and functions, the tasks for which each is suitable, and where the projects overlap. Attendees will come away with a better sense of where these three projects fit in the world of Xen virtualization.

1. James Bulpin
XenServer CTO
James.Bulpin@citrix.com
Xen Project User Summit - Xen, XenServer,
and XAPI: What’s the Difference?
@JamesBulpin
Russell Pavlicek
Xen Project Evangelist
Russell.Pavlicek@XenProject.org
@RCPavlicek

2. • Linux author/evangelist/speaker since 1995
• Formerly FOSS columnist for Infoworld,
Processor, panelist on The Linux Show
webcast, speaker at ~50 FOSS conferences
• Xen Project Evangelist hired by Citrix in
January 2013
• Xen user/admin/integrator/ tester since
2004
• XenSource startup veteran
• Leads Citrix XenServer technical strategy
About the Speakers...
Russ James

3. • …until you ask them
• Some days, it seems there is more confusion about the
naming conventions than about the software
• When some people talk about “Xen”, they mean “Xen
Project”, but others mean “XenServer”, and yet others
“XAPI”
• It is time to clear up the confusion
The Problem: Everyone Knows What Xen Is...

4. • The Leading Open Source Hypervisor
• Open Source – now and always!
• A Linux Foundation Collaborative Project since April 2013
• Celebrating its 10th anniversary
• Home for several subproject teams
What is the Xen Project?

5. Xen Project: A Short History

6. • The Xen Hypervisor: the main game
• PVOPS: (not technically a subproject, but…) allows Linux to
run paravirtualized on a hypervisor (Xen, VMware VMI, …)
• The Xen ARM Hypervisor: branching into new architecture
• XAPI Project: more on this later
• Mirage OS: focused appliances built on a specialized library
operating system (in incubation)
The Xen Project Subproject Teams

7. Xen Hypervisor: The Crux of the Xen Project
• Type 1 Hypervisor: Does not run in
the kernel
• VMs compete with other VMs for
resources, not with processes
• Architecture emphasizes security
• Uses toolstacks for Control Domain
to talk to Hypervisor
• Default is XL (improved on XM)
• Libvirt/VIRSH option
• No native GUI

8. Xen Project Corporate Members
Is your company listed here? Should it be?
If you are heavily invested in Xen, consider project membership.

9. • Nexus of information regarding the Xen Project
• Newly revamped and revised in April 2013
• Access to Articles, Blogs, Wiki, Q&A, Mailing Lists, etc.
• New monthly newsletter with highlights from the
community
• Sign up for the website and newsletter today, if you
haven’t already!
XenProject.org: The Hub of Information

10. Xen Project Mascot
Because a cute panda is a terrible thing to waste

11. • A distribution of Xen, the XAPI toolstack, Linux and other
components
• A “shrink-wrapped”, ready to run, virtualization platform
• Builds on basic Xen virtualization to provide high level
management:
Networking High availability
Storage Cluster management
User accounts Performance monitoring
If That’s Xen, What is XenServer?

12. • Started as “XenEnterprise”, a product of XenSource Inc.
– First released in 2006
– Initially a proprietary product built on top of the open-source
Xen hypervisor
• Evolved into XenServer, a product of Citrix
– Now up to version 6.2 (released June 2013)
• Became an open-source project in 2013
XenServer – a brief history

13. Xen
Linux Kernel XAPI
Storage
Manager
XenServer
Tools (PV
drivers)
HA
CentOS 5.x
AD Integration
XenCenter
XenServer – previously
Transfer VM
CIM Server
Qemu
Proprietary
OSS, public dev
Key:
OSS, non-public dev

14. Xen
Linux Kernel XAPI
Storage
Manager
XenServer
Tools (PV
drivers)
HA
CentOS 5.x
AD Integration
XenCenter
XenServer – after open sourcing
Proprietary
OSS
Key:
Transfer VM
CIM Server
Qemu

15. • A Citrix-led project
• Removing barriers to collaboration
• Roadmaps, designs and architectural plans discussed in the
open
• All code is public; contributions via mailing list and Github
pull requests
• More efficient ecosystem through access to design, code
and developers
XenServer.org – the open-source project

16. #1 a set of components
– XenCenter UI
– Windows PV drivers
– HA daemon
– vncterm
– …
#2 an integration/distribution of
components
– Choice of component versions
– Backporting of patches
– Configuration and tuning
– Packaging
– …
XenServer.org – two parts to it
But Xen and XAPI are Xen Project
components so XenServer developers
contribute to those projects and the results
are integrated and packaged into XenServer

17. • Citrix’s product release from the
Open Source project code
• Made available to all for free
• Optional commercial support offering
from Citrix
Citrix XenServer

18. • A toolstack for managing Xen system
– The xapi daemon and its friends; the “xe” CLI
• Works at a higher level than the Xen Project toolstack
– Clustering, storage/network management, host setup, …
• Open-sourced by Citrix in 2009
• Now part of the Xen Project in the Linux Foundation
• Useful for Xen users who want richer API-driven
management (such as under OpenStack clouds)
So What is XAPI?

19. “Xen Cloud Platform” – an overloaded term
• Meaning 1: a synonym for XAPI (particularly for packaged
versions)
• Meaning 2: XenServer-like binary ISOs
– Built to provide a distribution for xapi without non-FOSS
XenServer pieces
– Provided a wider feature set than the free edition of Citrix
XenServer which had certain features disabled
What is XCP?

20. • XCP and open-source XenServer will merge
– XenServer no longer disables features for non-paying users
• Users of XCP v1.6 are able to upgrade to XenServer
• XCP users will be getting a better deal than they had before
– No more delays to XCP releases
– Timely hotfixes that can be easily installed,
– A product that's even more open than it was before.
XCP (the ISO) is no more

21. And you thought this talk would be easy… ;)
And Now It Is QUIZ TIME!

22. Question: Xen, XenServer, or XAPI?

23. Answer: Xen (Xen Project Mascot)

24. Question: Xen, XenServer, or XAPI?

25. Answer: XenServer (XenCenter)

26. Question: Xen, XenCenter, or XAPI?

27. Answer: XenServer

28. Question: Xen, XenCenter, or XAPI?

29. Answer: Xen and XAPI

30. $ xe vdi-create
name-label=LogDisk
sr-uuid=6021e2b0-c72e-6e9e-01cc-ba3ed4f68be9
virtual-size=10GiB type=user
$ xe vbd-create device=2 type=Disk
vm-uuid=d2f6e2cd-8a98-7e1c-7a46-f4dcff3b56ce
vdi-uuid=cdd63557-89ad-4011-b638-e063f8b08298
$ xe vm-start vm=MyDHCPServer
Question: Xen, XenServer, or XAPI?

31. $ xe vdi-create
name-label=LogDisk
sr-uuid=6021e2b0-c72e-6e9e-01cc-ba3ed4f68be9
virtual-size=10GiB type=user
$ xe vbd-create device=2 type=Disk
vm-uuid=d2f6e2cd-8a98-7e1c-7a46-f4dcff3b56ce
vdi-uuid=cdd63557-89ad-4011-b638-e063f8b08298
$ xe vm-start vm=MyDHCPServer
Answer: XAPI (xe CLI)

32. # xl create -c /etc/xen/wheezy64
# xen-create-image
--genpass=0 --memory=1024M --noswap --dhcp
--password="xenroot" --pygrub --size=8G
--vcpus=2 --arch=amd64 --bridge=virbr0
--hostname=wheezy64 --lvm=vms
--mirror=http://cdn.debian.net/debian
--install-method=debootstrap
--dist=wheezy
Question: Xen, XenServer, or XAPI?

33. # xl create -c /etc/xen/wheezy64
# xen-create-image
--genpass=0 --memory=1024M --noswap --dhcp
--password="xenroot" --pygrub --size=8G
--vcpus=2 --arch=amd64 --bridge=virbr0
--hostname=wheezy64 --lvm=vms
--mirror=http://cdn.debian.net/debian
--install-method=debootstrap
--dist=wheezy
Answer: Xen (xl and command line utility)

34. Extra Credit: Xen, XenServer, or XAPI?

35. Answer: Trick Question!
Used by Xen and XenServer, but a separate
project entirely!

36. Thank You!
Slides available under CC-BY-SA 3.0
From www.slideshare.net/xen_com_mgr
@RCPavlicek
@JamesBulpin
@Xen_Org
• News: blog.XenProject.org
• Web: XenProject.org / www.XenServer.org
– Help for IRC, Lists, …
– Stackoverflow-like Q&A
• Wiki: wiki.XenProject.org
• Presentations: slideshare.net/xen_com_mgr
• Videos: vimeo.com/channels/xen